Development of a room temperature hydrogen storage material is vital for the realization of a hydrogen economy. Towards achieving this goal, we present the use of naturally occurring diatom frustule for the synthesis of a novel nanomaterial that can achieve a hydrogen storage capacity of similar to 4.83 wt% at 25 degrees C and similar to 20 bar H-2 equilibrium pressure. We have effectively combined the large surface area of few layer graphene(G), the unique physical and chemical properties of diatom frustules(D) such as chemical inertness and good porosity and the ability of transition metals and their alloys (Pd3Co) to adsorb large amounts of hydrogen. The resulting nanomaterial (Pd3Co-D(100)-G) has a surface area of 163.25 m(2)/g and pore volume of 0.84 cm(3)/g. The observations in the present study suggest that increased surface area and porosity play a key role in achieving high hydrogen storage capacity at relatively low H-2 equilibrium pressures and room temperature conditions. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.